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Questions tagged [rf]

Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.

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21 views

How can rectification improve signal? [on hold]

I read that a thermionic valve can improve a radio signal. Since the valve removes half of the signal, I was wondering how such improvement is obtained. Thank you
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70 views

why high frequency are blocked by walls but allowing low frequency? [on hold]

I recently came across the idea that walls block high frequency signal but it allows low frequency signal. Could anyone explain why this behaviour?
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1answer
63 views

Working of a Diode Ring

I am trying to understand the working of a Diode ring circuit from this Video I find difficulty in understanding how the circuit works. How is the voltage at the point marked below is equal to ...
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1answer
33 views

Estimate data transmission rate on a given frequency using FM

How can I estimate how much data can I transmit on a given radio frequency range using FM? My goal is to consider using radio to transmit data packages, and I want to evaluate bandwidth. Plus ...
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1answer
48 views

How do I find the return loss of a transformer from its 4-port S-parameter data?

I'm looking for information on the performance of Mini-Circuits T16-1-KK81+ transformer. The transformer is well-characterized, Mini-Circuits provided both insertion/return loss charts and raw S-...
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Does DiSEqC require a DC bias?

The DiSEqC (Di[gital] S[attelite] Eq[uipment] C[ontrol] specification (bus_spec.pdf within https://www.eutelsat.com/files/PDF/DiSEqC-documentation.zip) describes a tone-based serial data bus that can ...
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43 views

DC brush motor EMI

What kind of frequency does a DC brush motor generate? There are a few explanations online as to what causes EMI in DC brush motors (commutator sparking for example) and how to reduce it, but no ...
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1answer
50 views

What short range RF receiver/transmitter? [closed]

I want to have a receiver/transmitter to be able to operate up to 2-5 meters maximum lower the better is this possible? if not what is another way to have wireless communication in this range? Im ...
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3answers
57 views

Extending the NRF24 range / power

I have a NRF24L01 model with an included screw-on antenna and apparently also an integrated RF amplifier (something like this, image sourced from eBay seller top_electronic1980). I have a lot of ...
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RF signal WORMHOLE? All innovative ideas / thoughts / foreseen failures are welcome! [closed]

Imagine a Transceiver mounted to one side of a wall (surface #1) indoors. Directly on the other side of the wall (surface #2) is another transceiver. As a RF signal approaches the surface 1, is it ...
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Difference between a RFID reader's antenna and a conventional antenna

What are the differences between an RFID RHCP patch antenna and a conventional RHCP patch antenna? If there are no differences can I just refer to an RFID reader's antenna as an antenna?
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Wireless systems [closed]

A transmitter is designed to transmit a signal of bandwidth 1MHz, transmit frequency in the range 706MHz to 753MHz. the passband adds an extra 1MHz on each side. the filter stopbands begin 25MHz away ...
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1answer
36 views

Quality Factor and Frequency Bandwidth in a matching network

it is known that the Quality Factor appears in the formulas for transformation of an impedance series bipole to a parallel one. A simple example is this one: Now I have three questions: 1) I have ...
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How far does a PCB antenna need to be from a capacitive sensing touch button?

From my basic understanding, capacitive touch works by having a small voltage applied to a touch plane on a PCB, resulting in a uniform electrostatic field. When a conductor (human finger) touches the ...
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21 views

ADS Layout to Schematic

How can I switch this P_1Tone source with... This antenna designed on ADS Layout..
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1answer
45 views

How to calculate maximum effective radiated power in any direction for Galtronics small cell site

Answer Calculations from PE commissioned by AT&T: the GQ2410-06621 antenna does have 10 total input ports, however, our analysis of the AT&T DAS node includes only the frequencies and power ...
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1answer
67 views

Quality Factor Formula

I read on many books this formula to calculate the quality factor of a series between a resistance and a reactive component (L and/or C): Now let's consider the series between a resistance and a ...
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28 views

Time Domain Reflectometry and reflection coefficient graph

I know it is possible to see if there is a mismatch on a certain device (for instance a transmission line of length L connected to a load) by using the TDR (Time Domain Reflectometer). It allows to ...
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1answer
48 views

Voltage Doubler Capacitor Values

When designing a voltage doubler at RF frequencies... Should you pick Capacitor values that makes C1 and C2 impedance 50 ohms ?
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1answer
51 views

Active Mixer RF Input Power and Input IP3i, P1dB Question

I am new and learning in this field. The received signal is first amplified with SKY65404 LNA and secondly with HMC313 Amplifier. Lastly it is connected to Active Mixer ADL5801's RFIN pins. In ...
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1answer
28 views

FDTD simulation for beginners using matlab

My previous posts are as follows: 1.Mitigation of dead zones when applying circular polarized antenna 2.Standing waves modes inside a cavity resonator 3.Visual understanding of EM fields within a ...
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1answer
68 views

Can two Radar motion sensor, running next to each other, result a false detection?

I have two CDM324 Radar motion sensors. I want to run the two sensors close to each other. The transmitted frequency is roughly 24 GHz and I am afraid that a small shift in one sensor transmitted ...
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29 views

Amplifier for pulsed Radar motion sensor

I have a radar motion sensor, IPM-170. The output of the sensor is as follows: The AC motion signal is -+300uv and there is a DC bias around 150mv. I am applying the following circuit so I can run ...
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1answer
55 views

Does a Center-Tapped RF Balun Perform Better than Untapped Baluns?

To my knowledge, a conventional transformer is a balun - you simply connect a single-ended signal at the primary side, you get the balanced signal at the secondary side - magnetic coupling doesn't ...
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2answers
56 views

How to interpret data sheet for an RF 50 Ohm terminator, is it 2 Watt or is it 0.1 Watt

I am trying to find a suitable RF 50 Ohm terminator for my application. I think the following will work: http://www.amphenolrf.com/media/downloads/7034/132360.pdf I am a little uncertain though as ...
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1answer
41 views

Characteristic Impedance without transmission lines

let's consider this three port power divider: I saw somewhere that the reflection coefficient Г11 can be calculated with the formula Г11 = (Zin - Z0)/(Zin + Z0), where Z0 = 50 Ohm. Now my questions ...
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103 views

What is this radiation coming from my phone?

I've built myself a crude EMI probe: I then pointed it at the top part of my phone when the phone was powered on, and I saw the following waveforms on my scope. First off, there are spikes every ...
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40 views

Deriving microstrip stub equations

Do anyone know how to derive the microstrip stub equations for all four microstrip below ?
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1answer
57 views

Using open termination to intentionally reflect RF signal

Part of the calibration for an RF system we designed involves measuring the frequency response so that we can equalize the return. Part of this calibration requires measuring the reference response of ...
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24 views

How to determine received signal strength including reflections?

I have an RF system with known transmit power, transmit antenna gain, receive antenna gain, distance, and frequency (900MHz ISM band). I can calculate direct received signal strength based on those ...
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2answers
68 views

Does the 433 MHz transmitter/receiver, transmit the voltage?

The title, says it all... I would like to know if the 433 MHz transmitter/receiver (couldn't find a datasheet, here is all I found on it) transmits the voltage, ...
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2answers
41 views

AD8318 Maximum Input Voltage

let's consider AD8318, a chip which contains a logarithmic amplifier, often used for power measurements. I have read its datasheet and there is a thing that I do not understand: no maximum input RF ...
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1answer
67 views

Changing the receiving frequency of a cheap RC car [closed]

My kids both have a RC car and unfortunately they both work on the 27MhZ frequency range, which means they can't both play at the same time because of interference. I opened up one of the two cars ...
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4answers
65 views

Coax characteristic impedance measurement

How is physically possible to get the value of the characteristic impedance of a certain coaxial cable? Precisely, in my case I have a coax of 50Ohm impedance, and I need to cut it and connect some ...
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What is an equation that will show RF wave characteristics?

I want to show a RF wave on a spherical grid coordinate system. How can I show the RF wave when t = time and y = magnitude? I also want to show curvilinear coordinate transitions of the RF wave ...
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1answer
59 views

Multimode cavity resonator

From my previous posts Insight into cavity resonators, Visual understanding of EM fields within a rectangular metal container I have slowly gained a better insight into cavity resonators and thereof. ...
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2answers
78 views

Wave Propagation in Transmission Lines

let's consider this image (from AAC book, see here) The author wanted to show that a transmission line propagates not only voltage and current waves, but also an electromagnetic wave in the space ...
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Modulate/demodulate 125khz signal to 433Mhz transmitter module (2.5Ghz carrier)

I am trying to implement a project which consists of two circuits. Circuit A receives a 125khz AM signal and modulates it to 433Mhz CC1101 which then uses 2.4Ghz carrier to send at longer distance. ...
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radio Link works with laptop but not with PC

I have a complicated issue. I set my HM-TRP radio modules to use: 117Khz receive bandwidth, 39Khz deviation frequency and 38Kbps air and data rate. The attached picture is my basic room setup for ...
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1answer
37 views

Antenna's resistance: meaning and evaluation

When I studied elementary antenna's theory, I saw that the resistance (for simplicity let's consider only the resistive terms) of an antenna Ra is made of: 1) a parasitic resistance Rl, which causes ...
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1answer
49 views

RF External matching network - mixer IC

I have question about mixer IC (Max2335), datasheet: https://datasheets.maximintegrated.com/en/ds/MAX2335.pdf LNAOUT and MIXIN in pin description (p. 5) have notice: "Requires an external matching ...
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Input impedance of High - Frequency Amplifiers

I have a question about the choice of the input impedance of a high frequency amplifier. In general I know from elementary analog electronics courses that it is good for an amplifier (for instance an ...
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1answer
30 views

What are the appropriate pulse width and PRF for a pulsed Doppler sensor

I have a raw k-band transceiver, radar-based 24 GHz, motion detector, IPM-165. and here is the datasheet: https://www.innosent.de/fileadmin/media/dokumente/DATASHEETS_2016/Datenblatt_IPM-165_V8....
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RF sampling ADCs(ADC12DJ3200 ),PLLS and regulators placement and layout

I am novice in PCB component placement and layout. I have just started my career in Hardware design. We have designed a schematic for Data Acquisition System. In our design, we are using three RF ...
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2answers
331 views

Insight into cavity resonators

Modes of a waveguide As shown in the link above, they show how these modes work for various values of m, n, and p. However, where is the antenna/ source of radiation placed within the cavity? From ...
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2answers
239 views

Visual understanding of EM fields within a rectangular metal container

I have the following scenario setup inside a rectangular metal container. The container size is 12.03m by 2.39m by 1.84m (lxbxh). Additionally, inside the container I have placed 4 antennas equally ...
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2answers
98 views

Impedance mismatch vs Signal attenuation

I'm currently designing a 50Ω grounded coplanar waveguide (GCPW) which connects an antenna to an LTE modem. My question is: does there exist a standard graph/chart that attempts to generalise ...
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0answers
47 views

Current monitor for a High frequency signal

I'm working on a current monitoring circuit for a high frequency current monitoring application as shown in the schematic below, the requirements are as follows. Should be able to provide RMS current ...
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1answer
35 views

Video stream over RF and converting to Wifi

So, here is the scenario: I have to put a camera far away from my wifi internet hub and want to see the video on my cell phone. I know that I can put Wifi repeaters, but it's not a feasible solution. ...
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1answer
81 views

Broadband RF noise source/generator

I’m try to make a wideband noise source up to 150MHz, around 0dBm and as flat as possible, based on diode’s avalanche mechanism, plus some buffering and amplification stages. My questions: What is ...